Industrial furnace



Oct. 1l, 1932. B. G. HARMON INDUSTRIAL FURNACE Filed Nov. 25. '1931 wv v Patented Oct. 11, 1932 i UNITED STATES PATENT OFFICE BENJAHIN`G. HARMON, OF STON, ILLINOIS, ASSIGNOR TO THE GAS MACHINERY COMPANY, O'F CLEVELAND, OHIO, A CORPORATION OF OHIO INDUSTRIAL FURNACE Application le'd November 25, 1931.

A forging or rolling, furnaces for normalizing bars, sheets, and strips, furnaces for annealing, heat treating, and welding, and other forms of industrial furnaces, both of the continuous and intermittent types, by which the infiltration of atmospheric air to the combustion or heating chambers is prevented and the maintenance of a constant furnace atmosphere is thereby insured, with the production of quality products and without the use of an excessive amount of fuel. Particularly, the invention prevents the scaling of the stock and surface decarburization thereof.

Other forms of apparatus in which my imimprovements also improvements for pre-- venting the entrance of water vapor into the combustion chamber as well as preventing the 'infiltration of air.

The annexed drawing and the following v'description set forth invdetail certain means illustrating my invention, such means disclosing, however, only three of the various forms of apparatus in'which my improvements may be embodied. v

In said` annexed drawing:

`Figure 1 isa fragmentary vertical section of a rotary furnace in which my improvements are embodied; V

Figure 2 is a fragmentary horizontal section, taken in the plane indicated by the line 2 2, Figure 1;

Figure 3 is a fragmentary vertical section of a slab and billet reheating' furnace in Y. which certain of my improvements are embodied; and

Serial No. 577,317.

Figure 4 is a fragmentary vertical section of a car-type annealing and normalizing furnace embodying my improvements.

Referring to the annexed drawing in .which the same parts are indicated by the same respective numbers in the several views, an voil or gas-fired furnace l, Figures 1 and 2, has an exterior wall 2 surrounding a combustion chamber 3 below which is a hearth 4 rotated by any suitable means (not shown). The slugs or stock 5 are carried by the rotating hearth 4 from a charging opening to a discharge opening during the treating operation, as is well known toy those skilled in the art, the charging and discharging of the stock oftentimes being effected through the same4 opening. It is desirable to keep' the furnace atmosphere in the combustion chamber 3 substantially constant, preferably shghtly reducing so as to minimize the scaling, and it is further desirable to effect this result Without the use of an excessive amount of fuel.

Industrial furnaces of standard design are provided with waste gas flues and -I have shown this feature in Figures l and 2 and it A comprises upwardly-directed iues 11 formed inthe wall 2 and communicating with spaced vent ports 12 leading from the combustion chamber 3. I have provided these ports 12 at about the upper level of the hearth 4. Further, I have downwardly extended the flues 1l, as shown by the iue portions 11', and provided a circular base flue 13 which communicates with the bottom of the iue portions 11 and opens into the spacev between the wall 2 and the rotating hearth 4 and preferably at about the bottom of this space.

nasmuch as the discharge of the waste gases through the ports 12 and upwardly through the flues 11 creates an upward suction effect in the flue portions 11', any air which inflters between the wall 2 and the hearth 4 is drawn into the circular flue 13 nand upwardly through the flue portions 11 and discharged. through the ues 11 without entering the combustion chamber 3.

In the construction described, the products of combustion do not rush out of the combustion chamber 3 but are held there until.

sufficient pressure is built up within the-furnace to force them out through the ports 12.

, Thus, the products of combustion act as a blanket to exclude oxygenv and protect the slugs or stock from scaling. This method of protecting against scaling is cheaper and more effective than the use of raw gas and, especially at higher temperatures, avoids the dissociation of such gas with the production of nascent oxygeny which is the worst of all scaling agents.

I further provide a water seal covering the opening between the furnace wall 2 and the rotating hearth 4 in lieu of a sand seal or other forms of standard seals now known. This water seal is illustrated as an annular tank 6 bridging the space between and underneath the wall 2 and hearth 4 and into the water of which extend dip plates 9 and 10 suspended from the wall 2 and hearth 4, respectively. A water inlet 7 and outlet 8 are provided for maintaining a proper level in the tank 6. The circular flue 13 and the liuc portions 11 serve to carry olf also the vapor arising from the water in the seal and thus prevent the entrance of this vapor int-o the combustion chamber 3. For the purpose of somewhat obstructing and thus baliiing the space between the wall 2 and hearth 4,

and for the further purpose of positively diverting the upwardly-moving air and vapor into the circular flue 13, I form the dip plate 10 at its upper end with an angular flange 14 positioned at about the upper level of the iiue 13 and covering a material portion of the space between the furnace wall 2 and the hearth 4.

I The water seal 1s a means of preventing 1nfiltration of air while at the same time mini.A mizing power requirements and-the loss of heat from the heating chamber, and also protecting the furnace base from excessive heat.

I term my improvements in flues for preventing the infiltration of air and vapor into the combustion chamber a Siphon vent, and the principle thereof is also illustrated in Figures 3 and 4, as appliedto a slab and billet reheating furnace of non-rotary type, Figure 3; and to a car type furnace, Figure 4.- In Figure 3 a furnace 16 has side walls 17 surrounding a combustion chamber 18 at the base of which is a hearth (not shown). From the hearth the stock after being heated and soaked slides down an incline 19 by the force of gravity, and is discharged through laterally spaced doors 20, the entrance of air to the combustion chamber 18 beingpreventedduring this operation through the use of curtain chains 21 spaced'somewhat inwardly of the doors 20. In this form of furnace, also, a standard design of waste gas'lues 22 and vent ports 23 leading from the combustion chamber 18 are shown, and with these waste gas passages I have incorporated my siphon vent'flue improvements consisting in do'wnward extensions 22 of the liues 22 which open into the space 24 between the doors 20 and the curtain chain 21. Thus means are provided whereby thersuction effect of the upwardly-moving waste gases in the flues 22 tends to cause the air entering the space 24 to pass out by means of the flue portions 22 and ues 22 instead of passing into the combustion chamber 18. p

In Figure 3, I have also shown a watercooled lintel 25 at the base of the wall 17 and air-ejection means 26' in the flues 22. The lintel 25 serves to support the wall 17 and the doors 2O and the curtain chains 21. This lintel 25 also provides entrance ports for the lower extensions 22 of the iiues 22. The air injection means 26 serve under certain conditions to assist in the removal of the infiltered air, inasmuch as they can be utilized, if the stack draft pulling upon the atmosphere in chamber 18 is so strong as to prevent satisfactory passage of the waste gases through the vent ports 23.without the aid of the air injection means 26. Thus, the infiltered air is removed by the natural siphon draft, or by artificially-created suction, or by other equivalent means.

In Figure 4, a car type furnace 27 `with a wall 28 formed wit-h llues 29 and vent ports 30 effects the treatment of the stock upon a car 31 which is moved longitudinally of the furnace by any suitable means (not shown). The car 31 is exposed at the base to the action of cooling air. This air cannot enter the space between the car 31 and the wall 28 because of the water seals 32 into which dip the plates 33 depending from the car 31. The tanks 36 of the water seals 32 are suitably formed at the ends to permit the car 31 to enter with the dip plates 33 and any suitable means are provided for maintaining the water levely in the tanks 36. Any air which does infilter, and the vapor from the water seals, is drawn into the lues 29 by means of the base llues 37 and the downward extensions 29 of the flues 29 which communicate at the bottom with the base lues 37. For the purpose -of partially obstructing the spaces between thewall 28 and the car 31 and for diverting .the air and water vapor into the base lues 37, I providey the wall elements 38 having the flanges y39 extended into these spaces at about the level of thel top of the base iues 37.

What I claim is:

1. An industrial furnace having an enclosing wall and a hearth spaced from said wall, said furnace being formed with a combustion chamber communicating with the space between the wall and hearth, a conduit formed in the lower part of the furnace wall and opening( into said space,-and means for creating a suction in said conduit for the withdrawal of air and ,vapor from said space.'

2. An industrial furnace havingan enclos chamber, waste gas liues, vent ports from the combustion chamber formed in the furnace wall and communicating with said flues, and a conduit formed in the furnace wall and communicating at one end with the waste gas flues and communicating at the other end with the space between the wall and hearth i below said ports.

8. An industrial furnace having an enclosing wall and a hearth spaced from said wall, said furnace being formed with a combustion chamber, upwardly-leading waste gas fiues in the furnace wall, vent ports from the combustion chamber formed in the furnace Wall at about the upper level of the hearth and communicating with said flues, and a -Conduit communicating with the space between the wall and hearth and below the infiltered air from the space between the furnace wall and the' hearth into said conduit.

5. An industrial furnace having an enclosing wall and a hearth spaced from said wall, said furnace being formedl with a combustion chamber, waste gas flues=in the furnace wall, vent ports from the combustion chamber formed in the furnace walland communieating with said flues, the furnace wall being formed with stock openings having spaced' 'door and chain curtain closures, and conduits formed in the furnace wall and communicating at one end with the waste gas ilues and communicating at the other end i with the spaces between the doors 'and chain curtains. l.

6. An 1ndustrial furnace having an enclosing wall and a hearth spaced from said wall,

said furnace being formed with a combustion chamber, waste gas flues in the furnace wall, vent ports from the combustion chamber formed in the furnace wall and communicating with said flues, an air-ejection device located in said fiues, and a conduit formed in the furnace wall and communicating at one end with the'waste gas ilues and communicating at the other end with the space between the wall and hearth below said ports.

7. An industrial furnace having an enclosing wall and a hearth spaced from said Wall, said furnace being formed with a combstion chamber, waste gas ues in the furnace wall, vent ports from the combustion vchamber formed in the furnace wall and communicating with said flues, the furnace wall being formed with stock openings having spaced door and chain curtain closures, conduits formed in the furnace wall and communicating at one end with the Waste gas iues and communicating at the other end with the spaces `between the doors and chain curtains, and water-cooled wall members bounding said conduits adj acently above said spaces and supporting the furnace wall and the spaced door and chain curtain closures.

8. An industrial furnace having a casing wall and a rotating hearth within and spaced from said wall, said furnace being formed with a combustion chamber, a water seal covering the space between the wall and hearth, waste gas 'lues in the furnace wall, vent ports from the combustion chamber formed in the furnace wall and communica-ting with said flues, a wall conduit communicating with the space between the wall and hearth adjacent- 1y above the water seal, said conduit communicating with said waste gas iues, a dip plate extending from the furnace wall into the water seal, and a dip plate extending from the hearth into the water seal, said lastnamed dip plate having an angular flange extended into said space 'adjacently above the said wall conduit.

9. An industrial furnace having an enclosing wall and a hearth spaced from said wall, said furnace being formed with a combustion chamber communicating with the space betweenthe wall and hearth,the furnace wall being formed with stock openings having spaced door and chain curtain closures, conduits formed in the furnace wall and communicating with the spaces between the doors and chain curtains, and water-cooled wall members bounding said conduits adjacentlv above said spaces and supporting the spaced door and chain curtain closures.

Signed by me Athis 21st day of November,

BENJAMIN G. HARMON. 

